The Belgium international has struggled to hold down a regular start at San Paolo this season as head coach Rafael Benitez juggles his squad selection to compete in three competitions.
Mertens would like to play more for the Serie A club, but understands the reasoning behind Benitez's rotation policy.
Schalke have been linked with the 27-year-old winger, he says a move away is not something he is considering.
"Of course I want to play more, but I do understand where coach Benitez is coming from," he told Het Nieuwsblad.
"If you are a wide attacker in Italy, you need to do a lot of defending and running, so that is very exhausting. Therefore the coach rotates constantly.
"This week even Gonzalo Higuain was on the bench, so that says something. And the club is also apparently very satisfied. I really see no reason to move.
"I am not going to leave Napoli for another club during the January transfer window."
